新增 PostViewModel 及其相关逻辑

app/src/main/java/com/aiosman/riderpro/ui/post/PostViewModel.kt

@@ -0,0 +1,202 @@
+package com.aiosman.riderpro.ui.post
+
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.setValue
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import androidx.paging.Pager
+import androidx.paging.PagingConfig
+import androidx.paging.PagingData
+import androidx.paging.cachedIn
+import androidx.paging.map
+import com.aiosman.riderpro.data.AccountService
+import com.aiosman.riderpro.data.AccountServiceImpl
+import com.aiosman.riderpro.data.CommentRemoteDataSource
+import com.aiosman.riderpro.data.CommentService
+import com.aiosman.riderpro.data.CommentServiceImpl
+import com.aiosman.riderpro.data.MomentService
+import com.aiosman.riderpro.data.UserService
+import com.aiosman.riderpro.data.UserServiceImpl
+import com.aiosman.riderpro.entity.AccountProfileEntity
+import com.aiosman.riderpro.entity.CommentEntity
+import com.aiosman.riderpro.entity.CommentPagingSource
+import com.aiosman.riderpro.entity.MomentEntity
+import com.aiosman.riderpro.entity.MomentServiceImpl
+import com.aiosman.riderpro.ui.index.tabs.moment.MomentViewModel
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.asStateFlow
+import kotlinx.coroutines.flow.collectLatest
+import kotlinx.coroutines.launch
+
+object PostViewModel : ViewModel() {
+    var service: MomentService = MomentServiceImpl()
+    var commentService: CommentService = CommentServiceImpl()
+    var userService: UserService = UserServiceImpl()
+    private var _commentsFlow = MutableStateFlow<PagingData<CommentEntity>>(PagingData.empty())
+    val commentsFlow = _commentsFlow.asStateFlow()
+    var postId: String = ""
+
+    // 预加载的 moment
+
+    var accountProfileEntity by mutableStateOf<AccountProfileEntity?>(null)
+    var moment by mutableStateOf<MomentEntity?>(null)
+    var accountService: AccountService = AccountServiceImpl()
+
+    /**
+     * 预加载，在跳转到 PostScreen 之前设置好内容
+     */
+    fun preTransit(momentEntity: MomentEntity?) {
+        this.postId = momentEntity?.id.toString()
+        this.moment = momentEntity
+        viewModelScope.launch {
+            Pager(
+                config = PagingConfig(pageSize = 5, enablePlaceholders = false),
+                pagingSourceFactory = {
+                    CommentPagingSource(
+                        CommentRemoteDataSource(commentService),
+                        postId = postId.toInt()
+                    )
+                }
+            ).flow.cachedIn(viewModelScope).collectLatest {
+                _commentsFlow.value = it
+            }
+        }
+    }
+
+    fun reloadComment() {
+        viewModelScope.launch {
+            Pager(
+                config = PagingConfig(pageSize = 5, enablePlaceholders = false),
+                pagingSourceFactory = {
+                    CommentPagingSource(
+                        CommentRemoteDataSource(commentService),
+                        postId = postId.toInt()
+                    )
+                }
+            ).flow.cachedIn(viewModelScope).collectLatest {
+                _commentsFlow.value = it
+            }
+        }
+    }
+
+    suspend fun initData() {
+        moment = service.getMomentById(postId.toInt())
+//        moment?.let {
+//            accountProfileEntity = userService.getUserProfile(it.authorId.toString())
+//        }
+    }
+
+    suspend fun likeComment(commentId: Int) {
+        commentService.likeComment(commentId)
+        val currentPagingData = commentsFlow.value
+        val updatedPagingData = currentPagingData.map { comment ->
+            if (comment.id == commentId) {
+                comment.copy(liked = !comment.liked, likes = comment.likes + 1)
+            } else {
+                comment
+            }
+        }
+        _commentsFlow.value = updatedPagingData
+    }
+
+    suspend fun unlikeComment(commentId: Int) {
+        commentService.dislikeComment(commentId)
+        val currentPagingData = commentsFlow.value
+        val updatedPagingData = currentPagingData.map { comment ->
+            if (comment.id == commentId) {
+                comment.copy(liked = !comment.liked, likes = comment.likes - 1)
+            } else {
+                comment
+            }
+        }
+        _commentsFlow.value = updatedPagingData
+    }
+
+    suspend fun createComment(content: String) {
+        commentService.createComment(postId.toInt(), content)
+        this.moment = service.getMomentById(postId.toInt())
+        MomentViewModel.updateCommentCount(postId.toInt())
+        reloadComment()
+    }
+
+    suspend fun likeMoment() {
+        moment?.let {
+            service.likeMoment(it.id)
+            moment = moment?.copy(likeCount = moment?.likeCount?.plus(1) ?: 0, liked = true)
+            MomentViewModel.updateLikeCount(it.id)
+        }
+    }
+
+    suspend fun dislikeMoment() {
+        moment?.let {
+            service.dislikeMoment(it.id)
+            moment = moment?.copy(likeCount = moment?.likeCount?.minus(1) ?: 0, liked = false)
+            // update home list
+            MomentViewModel.updateDislikeMomentById(it.id)
+        }
+    }
+
+    suspend fun favoriteMoment() {
+        moment?.let {
+            service.favoriteMoment(it.id)
+            moment =
+                moment?.copy(favoriteCount = moment?.favoriteCount?.plus(1) ?: 0, isFavorite = true)
+        }
+    }
+
+    suspend fun unfavoriteMoment() {
+        moment?.let {
+            service.unfavoriteMoment(it.id)
+            moment = moment?.copy(
+                favoriteCount = moment?.favoriteCount?.minus(1) ?: 0,
+                isFavorite = false
+            )
+        }
+    }
+
+    suspend fun followUser() {
+        accountProfileEntity?.let {
+            userService.followUser(it.id.toString())
+            accountProfileEntity = accountProfileEntity?.copy(isFollowing = true)
+        }
+    }
+
+    suspend fun unfollowUser() {
+        accountProfileEntity?.let {
+            userService.unFollowUser(it.id.toString())
+            accountProfileEntity = accountProfileEntity?.copy(isFollowing = false)
+        }
+    }
+
+    var avatar: String? = null
+        get() {
+            accountProfileEntity?.avatar?.let {
+                return it
+            }
+            moment?.avatar?.let {
+                return it
+            }
+            return field
+        }
+    var nickname: String? = null
+        get() {
+            accountProfileEntity?.nickName?.let {
+                return it
+            }
+            moment?.nickname?.let {
+                return it
+            }
+            return field
+        }
+    fun deleteMoment(callback: () -> Unit) {
+        viewModelScope.launch {
+            moment?.let {
+                service.deleteMoment(it.id)
+                MomentViewModel.deleteMoment(it.id)
+            }
+            callback()
+        }
+    }
+
+}